Thermal insulation for outdoor heating pipes

The thickness of the thermal insulation layer.mm	Δt. ° C	Outer diameter of the pipeline( mm)
15	20	25	32	40	50	65	80	100	150
The value of the heat losses( per 1 running meter of the pipeline, W).
10	20	7.2	8.4	10	12	13.4	16.2	19	23	29	41
30	10.7	12.6	15	18	20.2	24.4	29	34	43	61
40	14.3	16.8	20	24	26.8	32.5	38	45	57	81
60	21.5	25.2	30	36	40.2	48.7	58	68	86	122
20	20	4.6	5.3	6.1	7.2	7.9	9.4	11	13	16	22
30	6.8	7.9	9.1	10.8	11.9	14.2	16	19	24	33
40	9.1	10.6	12.2	14.4	15.8	18.8	22	25	32	44
60	13.6	15.7	18.2	21.6	23.9	28.2	33	38	48	67
30	20	3.6	4.1	4.7	5.5	6	7	8	9	11	16
30	5.4	6.1	7.1	8.2	9	10.6	12	14	17	24
40	7.3	8.31	9.5	10.9	12	14	16	19	23	31
60	10.9	12.4	14.2	16.4	18	21	24	28	34	47
40	20	3.1	3.5	4	4.6	4.9	5.8	7	8	9	12
30	4.7	5.3	6	6.8	7.4	8.6	10	11	14	19
40	6.2	7.1	7.9	9.1	10	11.5	13	15	18	25
60	9.4	10.6	12	13.7	14.9	17.3	20	22	27	37

In the practice of private construction is not so often, but still there are situations where heating communications are required not only to dissolve in the premises of the main house, but also to extend them to other nearby buildings. It can be residential wings, outbuildings, summer kitchens, household or agricultural buildings, for example, used to keep pets or poultry. The option is not excluded when, on the contrary, the autonomous boiler house itself is located in a separate building, some distance from the main residential building. It happens that the house is connected to the central heating main, from which pipes are stretched to it.

The laying of heating pipes between buildings is possible in two ways - underground( channel or non-channel) and open. Less laborious is the process of installing a local heating main above the ground, and this option is used more often in self-construction. One of the main conditions of the system's efficiency is a well-planned and high-quality thermal insulation for outdoor heating pipes. This issue will be discussed in this publication.

What is the thermal insulation of pipes and the main requirements for it

It would seem, nonsense - why heat the already almost always hot pipes of the heating system? Perhaps someone can mislead a kind of "play on words."In this case, of course, it will be more correct to conduct a conversation, using the term "thermal insulation".

Thermal insulation works on any pipelines have two main objectives:

• If the pipes are used in heating or hot water supply systems, the reduction of heat losses, maintenance of the required temperature of the pumped liquid comes to the fore. The same principle is also true for industrial or laboratory facilities, where the technology requires the maintenance of a certain temperature of the substance transmitted through the pipes.
• For pipelines of cold water supply or sewerage systems, the main factor is the insulation, it prevents the falling in the pipes below the critical temperature, preventing the freezing, leading to system failure and deformation of the pipes.

By the way, this precaution is required for heating mains and for hot water pipes - no one is completely immune from emergency situations on the boiler equipment.

The very cylindrical shape of the pipes predetermines a very large area of ​​constant heat exchange with the environment, which means significant heat loss. And they, naturally, grow as the diameter of the pipeline increases. The following table clearly shows how the heat loss varies with the difference in temperature inside and outside the pipe( column Δt °), the diameter of the pipes and the thickness of the thermal insulation layer( data are given taking into account the use of a thermal insulation material with an average thermal conductivity λ = 0.04W / m × ° C).

As the thickness of the insulation layer grows, the overall heat loss is reduced. However, note that even a sufficiently thick layer of 40 mm does not exclude heat losses completely. Conclusion one - it is necessary to strive to use insulating materials with the minimum possible coefficient of thermal conductivity - this is one of the main requirements for thermal insulation of pipelines.

Sometimes a heating system is required!

When laying water or sewer lines, it happens that, due to the local climate or specific installation conditions, one thermal insulation is clearly not enough. We have to resort to forced heating of the water pipe, to the installation of heating cables - this topic is discussed in more detail in the special publication of our portal.

• The material used for the thermal insulation of pipes, if possible, must have hydrophobic qualities. There will not be much current from a heater that has been soaked in water - it will not prevent heat loss, and soon it will collapse under the influence of negative temperatures.
• Thermal insulation construction must have reliable external protection. First, it needs protection from atmospheric moisture, especially if a heater is used that can actively absorb water. Secondly, the materials should be closed from the effects of the ultraviolet spectrum of sunlight, acting on them is disastrous. Thirdly, we should not forget about the wind load, capable of violating the integrity of thermal insulation. And, fourthly, there remains a factor of external mechanical influence, involuntary, including from the part of animals, or because of banal manifestations of vandalism.

. Besides, for any owner of a private house, the moments of aesthetic appearance of the paved heating path are certainly not indifferent.

• Any thermo-insulating material applied on heating mains must have a range of operating temperatures that corresponds to the actual conditions of use.
• An important requirement for insulating material and its external lining is the durability of use. Nobody will want to return to the problems of thermal insulation of pipes, even every few years.
• From a practical point of view, one of the basic requirements is the ease of installation of thermal insulation, and in any position and on any complex site. Fortunately, in this regard, manufacturers are not tired of pleasing the easy-to-use developments.
• An important requirement for thermal insulation - its materials must themselves be chemically inert, and not enter into any reaction with the surface of the pipes. Such compatibility is the key to the duration of trouble-free operation.

The issue of cost is also very important. But in this regard, the spread of prices for specialized insulants for pipes is very large.

What materials are used to insulate the aboveground heating mains

The choice of thermal insulation materials for heating pipes with their external installation is quite large. They can be roll type or in the form of mats, they can be given a cylindrical or other shaped form convenient for installation, there are heaters that are applied in a liquid form and acquire their properties only after hardening.

Thermal insulation with foamed polyethylene

Foamed polyethylene is rightly referred to very effective thermal insulators. And what's more, the cost of this material is one of the lowest.

The thermal conductivity of foamed polyethylene usually in the range of 0.035 W / m × ° C is a very good indicator. The smallest isolated bubbles filled with gas create an elastic structure, and with such material, if its roll variety is purchased, it is very convenient to work on complicated pipe sections.

Such a structure becomes a reliable barrier to moisture - if properly installed, neither water nor water vapor through it can penetrate to the pipe walls.

The density of foam is low( about 30 - 35 kg / m³), ​​and thermal insulation does not make pipes worse.

The material with some assumption can be classified as low-risk in terms of flammability - it usually refers to the G-2 class, that is, it is very difficult to ignite, and without an external flame it quickly damps. Moreover, combustion products, unlike many other thermal insulators, do not pose any serious toxic hazard to humans.

Rolled foamed polyethylene for insulation of external heating mains will be both inconvenient and unprofitable - it will be necessary to wind a few layers to achieve the required thickness of thermal insulation. Much more convenient in work material in the form of sleeves( cylinders), which provides an internal channel, corresponding to the diameter of the insulated pipe. To put on pipes, usually on the length of the cylinder on the wall an incision is made, which after installation can be sealed with a reliable tape.

A more effective type of foam is penofol, which has a foil layer on one side. This brilliant coating becomes a kind of thermo-reflector, which significantly improves the insulation properties of the material. In addition, it is an additional barrier against moisture penetration.

Penofol can also be roll type or in the form of shaped cylindrical elements - especially for the thermal insulation of pipes for various purposes.

And all foamed polyethylene for thermal insulation of heat pipes is used infrequently. It is more suitable for other communications. The reason for this is a rather low operating temperature range. So.if you look at the physical characteristics, then the upper limit balances somewhere on the verge of 75 ÷ 85 degrees - higher than possible structural violations and the appearance of deformations. For autonomous heating, most often, this temperature is enough, however, on the verge, and for central - thermostability is clearly not enough.

Insulating elements from expanded polystyrene

All known expanded polystyrene( commonly referred to as foam plastic) is widely used for a variety of types of thermal insulation work. The insulation of pipes is also an exception, for this purpose special details are made from foam.

pipes. Typically, these are semi-cylinders( for segments of large diameters there can be segments of one third of the circumference of 120 °), which are fitted with a tongue-and-groove connection for assembly in a single structure. Such a configuration allows completely, along the whole surface of the pipe, to provide reliable thermal insulation, without the remaining "cold bridges".

In everyday speech, such details are called "shells" - for the apparent similarity with it. Many of its types are produced, for various outer diameter of insulated pipes and different thickness of thermal insulation layer. Usually the length of the parts is 1000 or 2000 mm.

Polystyrene type PSB-C of various grades is used for production - from PSB-S-15 to PSB-S-35.The main parameters of this material are given in the table below:

Estimated Material Parameters	Estimated Material Parameters
PSB-C-15U	PSB-C-15	PSB-C-25	PSB-C-35	PSB-C-50
Density( kg / m³)	up to 10	up to 15	15.1 ÷ 25	25.1 ÷ 35	35.1 ÷ 50
Compressive strength at 10% linear deformation( MPa, not less)	0.05	0.06	0.08	0.16	0.2
Flexural strength( MPa, not less than)	0.08	0.12	0.17	0.36	0.35
Thermal conductivity in dry condition at 25 ° C( W /( m × ° K))	0,043	0,042	0,039	0,037	0,036
Water absorption for 24 hours( % by volume, no more)	3	2	2	2	2
Humidity( %, no more)	2.4	2.4	2.4	2.4	2.4

Advantages of the foam as insulating material have been known for a long time:

• It has a low coefficient of thermal conductivity.
• The low weight of the material greatly simplifies the insulation work, for which no special mechanisms or devices are required.
• The material is biologically inert - it will not be a nutrient medium for the formation of mold or fungus.
• Moisture absorption is negligible.
• The material is easy to cut, fit to the desired size.
• Polyfoam is chemically inert, absolutely safe for pipe walls, from whatever material they are made.
• One of the key advantages - polystyrene refers to the most inexpensive heaters.

However, many of its drawbacks:

• First of all - it's a low level of fire safety. The material can not be called incombustible and does not spread the flame. That is why, when using it to insulate ground pipelines, fire breaks should always be left.
• The material does not have elasticity, and it is convenient to use it only on straight sections of the pipe. True, you can find special curly details.

• Polyfoam is not a strong material - it can easily be destroyed under external influence. Ultraviolet radiation also acts on it negatively. In a word, the aboveground sections of the pipe, insulated with expanded polystyrene shell, will necessarily require additional protection in the form of a metal casing.

Usually in stores where the foam plastic shell is sold, they also offer galvanized sheets cut into the right size, corresponding to the diameter of the insulation. You can use an aluminum shell, although it is certainly much more expensive. The sheets can be fixed with self-tapping screws or clamps - the resulting casing will create simultaneously anti-vandal, anti-wind, waterproofing protection and a barrier from sunlight.

• And yet, even this is not the main thing. The upper limit of normal operating temperatures is only around 75 ° C, after which linear and spatial deformation of parts can begin. Whatever one may say, for heating this value may not be enough. Probably, it makes sense to look for a more reliable option.

Warming of pipes with mineral wool or products based on it

The most "ancient" method of thermal insulation of external pipelines - using mineral wool. By the way, it is also the most budgetary, if it is not possible to purchase a foam plastic shell.

For thermal insulation of pipelines, various types of mineral wool are used - glass wool, stone( basalt) and slag wool. Slag is the least preferred: first, it absorbs moisture most actively, and secondly, its residual acidity can be very destructive to steel pipes. Even the cheapness of this wool does not justify the risks of its application.

But mineral wool based on basalt or glass fibers will do the trick. It has good indicators of thermal resistance to heat transfer, high chemical stability, the material is elastic, and it is easy to lay even on complex sections of pipelines. Another advantage - you can be, in principle, completely calm in terms of fire safety. Preheat the mineral wool to the degree of ignition in conditions of an external heating main - almost impossible. Even exposure to an open flame will not cause a fire. That is why the mineral wool is used to fill fire breaks when using other pipe heaters.

The main disadvantage of mineral wool is the high absorbency of water( basalt is less susceptible to this "disease").Hence, any pipeline will require mandatory protection against moisture. In addition, the structure of cotton wool is not resistant to mechanical influences, it is easily destroyed, and it should be protected with a strong casing.

Usually, a strong polyethylene film is used, which is securely wrapped with a layer of insulation, with an obligatory overlap of the strips for 400 ÷ 500 mm, and then all of this is covered with metal sheets - exactly by analogy with a styrofoam shell. As a waterproofing can also be used roofing material - it will be enough 100 ÷ 150 mm overlapping one strip on the other.

Existing GOSTs define the thickness of protective metal coatings for open pipeline sections for any type of thermal insulation materials used:

Material of protective coating layer	Minimum metal thickness, with external insulation diameter
350 or less	Over 350 and up to 600	Over 600 and up to 1600
Stainless steel strips and sheets	0.5	0.5	0.8
Sheet steel sheets, galvanized or coated with polymers	0.5	0.8	0.8
Sheets made of aluminum or of ayuminievyh alloys	0.3	0.5	0.8
tapes aluminum or aluminum alloy	0.25	-	-

Thus, despite the apparent low cost price of the insulation, its complete styling will require considerable additional costs.

Mineral wool for insulation of pipelines can act in a different capacity - it serves as a material for the manufacture of finished thermoinsulating parts, in analogy with cylinders made of foam polyethylene. And such products are produced both for direct pipeline sections, and for turns, tees, etc.

pipe. Typically, such insulation parts are made from the most dense - basalt mineral wool, have an external foil coating that immediately removes the problem of waterproofing and increases the efficiency of insulation. But from the outer casing it will still not be possible to leave - a thin layer of foil from accidental or deliberate mechanical action will not protect.

Heating of heating mains with polyurethane foam

One of the most effective and safe in use modern insulating materials is polyurethane foam. He - a lot of various advantages, so the material is used on almost any structure that requires reliable insulation.

What are the features of polyurethane foam - insulation?

In order not to repeat, it is advisable to recommend the reader to read more about the special article of the portal, which is entirely devoted to advantages and disadvantages of foamed polyurethane, as a thermal insulation material.

Polyurethane foam for insulation of pipelines can be applied in various types.

• Widely used PPU-shell, usually having an external foil coating. It can be demountable, consisting of half-cylinders with passe-crest locks, or, for pipes of small diameter - with a cut along the length and a special valve with a self-adhesive rear surface, which greatly simplifies the installation of insulation.

• Another way of thermal insulation of heating mains with polyurethane foam is spraying it in liquid form with the help of special equipment. The created layer of foam after full hardening becomes an excellent insulation. Especially convenient is a similar technology at complex junctions, pipe turns, in knots with shut-off and control valves, etc.

The advantage of this technology is that excellent waterproofing and anti-corrosion protection are created thanks to excellent adhesion of polyurethane foam spraying to the pipe surface. True, polyurethane foam itself also requires mandatory protection - from ultraviolet rays, so you can not do without a casing again.

• Well, if you need to lay a sufficiently long heating main, then probably the most optimal choice will be the use of pre-insulated( pre-insulated) pipes.

In fact, such pipes are a multilayer structure assembled in the factory:

- The inner layer is actually the steel pipe of the required diameter, through which heat transfer is carried out.

- External coating - protective. It can be polymer( for laying a heating path in the earth's thickness) or metal galvanized - what is required for open sections of the pipeline.

- A monolithic, seamless layer of polyurethane foam is installed between the pipe and the casing, performing the function of effective thermal insulation.

From both ends of the pipe there is an assembly area for welding operations during the heat pipeline assembly. Its length is calculated in such a way that the heat flux from the welding arc does not damage the polyurethane foam layer.

After the installation, the remaining uninsulated sections are primed, covered with a polyurethane foam shell, and then with metal belts, comparing the coating with the overall outer jacket of the pipe. Often it is in such areas that fire breaks are organized - they are densely filled with mineral wool, then waterproofed with a ruberoid and still covered with a steel or aluminum casing.

The standards set a certain assortment of such sandwich pipes, that is, it is possible to purchase products of the required nominal diameter with the optimal( conventional or reinforced) thermal insulation.

Outer diameter of steel pipe and minimum thickness of its wall( mm)	Sheath dimensions of galvanized sheet steel	Design thickness of thermal insulation layer of polyurethane foam( mm)
nominal outer diameter( mm)	minimum thickness of steel sheet( mm)
32 × 3,0	100;125;140	0.55	46.0;53.5
38 × 3.0	125;140	0.55	43.0;50.5
45 × 3.0	125;140	0.55	39.5;47.0
57 X 3.0
0.55	40.9
76 × 3.0	160	0.55	41.4
89 × 4.0	180	0.6	44.9
108 × 4,0	200	0.6	45.4
133 × 4,0	225	0.6	45.4
159 × 4.5	250	0.7	44.8
219 × 6.0	315	0.7	47.3
273 × 7.0	400	0.8	62.7
325 × 7.0	450	0.8	61.7

Manufacturers offer such sandwich tubesnot only for straight sections, but also for tees, turns, compensators, etc.

The cost of such pre-insulated pipes is quite high, but with their acquisition and installation a whole complex of problems is solved immediately. So such costs are seen as fully justified.

Video: the process of production of pre-insulated pipes

Insulation - foamed rubber

Very popular in recent years are thermo-insulating materials and products made of synthetic foamed rubber. This material has a number of advantages that lead him to leadership positions in the issues of insulation of pipelines, including not only heating mains, but also more responsible ones - on complex technological lines, in machine, aircraft and shipbuilding:

• Foamed rubber is very elastic, but at the same time has a large margin of tear strength.
• The density of the material is only 40 to 80 kg / m³.
• Low coefficient of thermal conductivity provides very effective thermal insulation.
• The material does not shrink with time, completely retaining its original shape and volume.
• Foamed rubber is difficult to ignite and has the property of rapid self-extinguishing.
• The material is chemically and biologically inert, it does not show mold or fungal foci, nests of insects or rodents.
• The most important quality is practically absolute water and vapor tightness. Thus, the insulation layer immediately becomes an excellent waterproofing for the pipe surface.

Such thermal insulation can be produced as hollow tubes with an internal diameter of 6 to 160 mm and a thickness of the insulation layer from 6 to 32 mm, or in the form of sheets, which are often attached to one side with a function"Self-adhesive".

Description of parameters	Values ​​of
Length of finished tubes, mm:	1000 or 2000
Color	black or silver, depending on the type of protective coating
Temperature range of application:	-50 to + 110 ° C
Thermal conductivity, W /( m× ° C):	λ≤0,036 at 0 ° C
λ≤0,039 at +40 ° C
Resistance to vapor permeability:	μ≥7000
Degree of fire hazard	Group G1
Permitted length change:	± 1.5%

But for those located outdoorsThe slope is especially suitable for ready-made insulation elements made using the "Armaflex ACE" technology, which have a special protective coating "ArmaChek".

"ArmaChek" coating can be of several types, for example:

• "Arma-Chek Silver" is a multilayer PVC-based shell with silver reflective sputtering. This coating provides excellent insulation protection against both mechanical and ultraviolet radiation.
• The black "Arma-Chek D" coating has a fiberglass high-strength, but excellent flexibility base. This is an excellent protection against all possible chemical, weather, mechanical influences that will keep the heating pipe intact.

Typically, such products using the technology "ArmaChek" have self-adhesive valves, sealingly "sealing" the heating cylinder on the body of the pipe. The curly elements are also produced, allowing to carry out installation on difficult sections of the heating main. The skillful use of such thermal insulation allows it to be mounted quickly and reliably without resorting to the creation of an additional external protective casing - it is simply not necessary.

The only thing that probably hinders the widespread use of such insulating products for pipelines is the still prohibitively high price for genuine, "branded" products.

New direction in insulation - heat-insulating paint

Another modern technology of insulation should not be missed. And it is all the more pleasant to talk about it, since it is the development of Russian scientists. This is a ceramic liquid insulation, which is still known as a heat-insulating paint.

This, without a doubt, is an "alien" from the sphere of space technologies. It is in this scientific and technical industry that the issues of thermal insulation from critically low( in outer space) or high( when launching ships and landing descent vehicles) are particularly acute.

Thermal insulation qualities of ultra-thin coatings seem fantastic. At the same time, such a coating becomes excellent hydro and vapor insulation, protecting the pipe from all possible external influences. Well, the heating main itself takes a well-groomed, nice look.

The paint itself is a suspension of microscopic, vacuum-filled silicone and ceramic capsules suspended in a liquid state in a special composition including acrylic, rubber and other components. After application and drying of the composition on the surface of the pipe, a thin elastic film is formed, which has outstanding thermal insulation properties.

20 and above	19 and below
Mineral wool piercing plates	120	0,045	0,044 ÷ 0,035	From-180 to + 450 for mats, on fabric, mesh, fiberglass canvas;up to + 700 - on metal mesh	Non-flammable
150	0,05	0,048 ÷ 0,037
Mineral wool heat-insulating plates on synthetic binder	65	0.04	0,039 ÷ 0,03	From -60 to + 400	Non-flammable
95	0,043	0,042 ÷ 0,031
120		0.044 0.043 ÷ 0.032	from - 180 to + 400
180		0.052 0.051 ÷ 0.038
Insulating foamed rubber etilenpolipropilenovogo "Aeroflex»	60	0,034	0,033	from - 55 to + 125
Semicylinders readily flammable and cylinders mineral	50	0,04	0,039 ÷ 0,029	From - 180 to + 400	Non-combustible
80	0,044	0,043 ÷ 0,032
100	0,049	0,048 ÷ 0,036
150	0,05	0,049 ÷ 0,035
200	0,053	0,052 ÷ 0,038
Heat insulation cable from mineral wool	200	0,056	0,055 ÷ 0,04	From-180 to + 600 Vdepending on the material of the mesh tube	In the mesh tubes made of metal wire and glass thread - non-flammable, remaining lightly combustible
Mats made of glass staple fiber on synthetic binder	50	0,04	0,039 ÷ 0,029	From -60 to + 180	Non-flammable
70	0,042	0,041÷ 0,03
Mats and cotton wool from supertonglass fiber without binder	70	0,033	0,032 ÷ 0,024	From - 180 to + 400	Nonflammable
Mats and wool made of superthin basalt fiber without binder	80	0,032	0,031 ÷ 0,024	From-180 to + 600	Non-combustible
Sand perlitic, expanded, fine	110	0,052	0,051 ÷ 0,038	From-180 to + 875	Non-flammable
150	0,055	0,054 ÷ 0,04
225	0,058	0,057 ÷ 0,042
Thermal insulation products of expanded polystyrene	30	0,033	0,032 ÷ 0,024	From-180 to + 70	Combustible
50	0,036	0,035 ÷ 0,026
100	0,041	0,04 ÷ 0,03
Thermal insulation products of polyurethane foam	40	0,030	0,029 ÷ 0,024	From - 180 to + 130	Combustible
50	0,032	0,031 ÷ 0,025
70	0,037	0,036 ÷ 0,027
Thermal insulation products of expanded polyethylene	50	0,035	0,033	From -70 to + 70	Combustible
Thermal insulation material or product	Average density in the finished structure, kg / m3	Thermal conductivity of thermal insulation material( W /( m × ° C)) for surfaces with temperature( ° C)	Operating temperature range, ° C	Combustibility group

Dimensions Nos.	Unit of measurement	Value
Paint color	white( can be customized)
Appearance after application and complete hardening	matt, flat, uniform surface
Flexibility of the bending film	mm	1
Coating adhesion on tear strength from paintedsurface
- to the concrete surface	MPa	1.28
- to the brick surface	MPa	2
- to steel	MPa	1.2
Coating resistance to the effect of temperature difference from -40C to + 80 ° C	unchanged
Coating resistance to +200 ° C for 1, 5 hours	yellowing, cracks, peeling and bubbles none
Durability for concrete and metal surfaces in the moderately cold climatic region( Moscow)	years	no less than 10
Thermal conductivity	W / m ° C	0,0012
Vapor permeability	mg / m × h × Pa	0.03
Water absorption for 24 hours	% by volume	2
Operating temperature range	° C	from -60 to+ 260

This coating is not requiredbuet additional protective layers - it is strong enough to deal with all the influences on its own.

A liquid insulator is realized in plastic cans( buckets), just like a conventional paint. There are several manufacturers, and among the domestic ones you can especially note the brands "Armor" and "Corundum".

pipes. It is possible to apply such a thermal spray by aerosol spraying or by the usual method - roller and brush. The number of layers depends on the operating conditions of the heating main, the climatic region, the diameter of the pipes, the average temperature of the pumped coolant.

Many experts believe that such heaters over time to replace the usual thermal insulation materials on a mineral or organic basis.

Video: presentation of ultra-thin thermal insulation of the brand "Corund"

What is the thickness of heat insulation of the heating main is necessary

Summing up the review of the materials used for thermal insulation of heating pipes, you can use the performance of the most popular of them in the table - for clarity of comparison:

But for sure the inquisitive reader will ask:and where the answer to one of the main emerging questions - what should be the thickness of the insulation?

This question is quite complex, and there is no unambiguous answer to it. If you want, you can use the cumbersome calculation formulas, but they are probably understandable only to qualified heat engineers. However, not everything is so scary.

Manufacturers of finished thermo-insulating products( shells, cylinders, etc.) usually lay the required thickness, calculated for a specific region. And if a mineral wool insulation is used, you can use the data in the tables, which are given in the special Code of Regulations, which is designed specifically for the thermal insulation of pipelines and process equipment. This document can be easily found on the network by specifying the search query "SP 41-103-2000".

Here, for example, the table in this handbook concerning the above-ground location of the pipeline in the Central region of Russia, using mats made of M-35 glass staple fiber, 50:

Outside diameter pipe, mm	Heating pipe type
feed	return	feed	return	feed	return
Average temperature mode, ° C
65	50	90	50	110	50
Required insulation thickness, mm
45	50	50	45	45	40	40
57	58	58	48	48	45	45
76	67	67	51	51	50	50
89	66	66	53	53	50	50
108	62	62	58	58	55	55
133	68	68	65	65	61	61
159	74	74	64	64	68	68
219	78	78	76	76	82	82
273	82	82	84	84	92	92
325	80	80	87	87	93	93

In the same way, you can find the required parameters for other materials. By the way, the same Code of Rules does not recommend significantly exceeding the specified thickness. Moreover, the maximum values ​​of the insulating layer for pipelines are also determined:

Outer diameter of the pipeline, mm	Limit thickness of the thermal insulation layer, mm
temperature 19 ° C and below	temperature 20 ° C or more
18	80	80
25	120	120
32	140	140
45	140	140
57	150	150
76	160	160
89	180	170
108	180	180
133	200	200
159	220	220
219	230	230
273	240	230
325	240	240

However, do not forget about one important nuance. The fact is that any insulation with a fibrous structure will inevitably shrink with time. And this means that after a certain period of its thickness may not be enough for reliable thermal insulation of the heating main. The only way out is to take into account this correction for shrinkage even during the installation of insulation.

For calculation, the following formula can be used:

H =( ( D + h ):( D + 2 h )) × h × Kc

H is the thickness of the mineral wool layer, taking into account the correction for compaction.

D - outer diameter of the pipe to be insulated;

h - required thickness of insulation according to the table of the Code of Rules.

Кс - the shrinkage factor( seal) of the fibrous insulation. It is a calculated constant, the value of which can be taken from the table below:

Thermal insulation materials and products	Sealing factor Kc.
Mineral wool matt pads	1.2
Heat insulation mats "TECHMAT"	1,35 ÷ 1,2
Mats and canvases made of superthin basalt fiber for laying on pipelines and equipment with conditional pass, mm:
• DN	3
̶ same, at medium density50-60 kg / m3	1,5
• DN ≥ 800 at an average density of 23 kg / m3	2
̶ same with an average density of 50-60 kg / m3	1,5
Mats made of glass staple fiber on a synthetic binder brand:
• M-45, 35, 25	1.6
• M-15	2.6
Mats from the glass staff"URSA" brand:
• M-11:
̶ for pipes with DN up to 40 mm	4,0
̶ for pipes with DN from 50 mm and higher	3,6
• M-15, M-17	2.6
• M-25:
̶ for pipes with DN up to 100 mm	1.8
̶ for pipes with DN from 100 to 250 mm	1,6
̶ for pipes with over 250 mm	1,5
Mineral wool boards with synthetic binding brand:
• 35, 50	1.5
• 75	1.2
• 100	1.10
• 125	1.05
Glass staple fiber slabs of the brand:
• P-30	1.1
• P-15,P-17 and P-20	1.2

To helpinterested reader, below is placed a special calculator, in which this ratio is already laid. It is necessary to enter the requested parameters - and immediately get the required thickness of mineral wool insulation taking into account the correction.

Calculator for calculating the thickness of the insulation of the pipe with mineral wool, taking into account shrinkage of the material